I will be driving from Ft. Smith MT to Craig MT with a buddy this summer. We have a guides lined up for the two destinations, but we are looking for some suggestions as to where to stop to fish (wading with public access) during the drive. I suspect we will be taking I 90 across the state.
Any suggestions?

The big questions would be how much time do you have and what month of summer? Because from here to there are a lot of options, but the Yellowstone is the only one "along" I90. That being said the "Stone" is right there From Livingstone to Columbus (after that it gets kinda murkey) though is a tough wade in the summer months best to be floated.

My neck of the woods (Columbus exit) has the Stillwater, Rosebuds (Laurel exit) Rock Creek. - All which are great for wading depending on when runoff ends.

You have Three Forks and Four Corners too with the Jefferson, Madison, Gallatin Right there off of I90. I know Gallatin can have some great wade fishing might be crowded due to easy access though.

Fish the mouth of the Shields river where it flows into the Yellowstone. I've had good luck there. I would also recommend, if it is just a couple of hour stop for which you are looking, don't head north to Townsend when you head to Helena/Craig. Instead go up through Boulder. The Boulder River (there are two. I'm talking about the one near Boulder) is not known as a great fishery. However, there are some great public access spots within the past 7 or 8 miles before Boulder that have given me some great fishing. I'm not talking monsters; but, I am talking occasions where I have been able to spend an hour or so and been able to catch a couple of dozen "fun little trout".

Fish the mouth of the Shields river where it flows into the Yellowstone. I've had good luck there. I would also recommend, if it is just a couple of hour stop for which you are looking, don't head north to Townsend when you head to Helena/Craig. Instead go up through Boulder. The Boulder River (there are two. I'm talking about the one near Boulder) is not known as a great fishery. However, there are some great public access spots within the past 7 or 8 miles before Boulder that have given me some great fishing. I'm not talking monsters; but, I am talking occasions where I have been able to spend an hour or so and been able to catch a couple of dozen "fun little trout".

Sounds like my choice if it were my trip. That is floating two great rivers with some good creek fishing on the dry in between. I would say come fish here but runoff can hit us as late as July. Though it's been heating up fast..

If it was me, I would head through Red lodge, over the Beartooth Highway to Cooke City and fish in the park. Then fish the Yellowstone to Livingston and get back on I 90. This may take more than 2 days though. If you miss the turn off and end up in Cody you could fish the Shoshone and enter the park from the east and then fish your way to Jackson where you will have to fish the Snake towards the west and then your not that far from the Henrys Fork.....which is still on the way to the Missouri...... or fish both Boulder rivers, the one south of Big Timber and the next day farther west out of Boulder, Mt. It will be a great trip.

If it was me, I would head through Red lodge, over the Beartooth Highway to Cooke City and fish in the park. Then fish the Yellowstone to Livingston and get back on I 90. This may take more than 2 days though. If you miss the turn off and end up in Cody you could fish the Shoshone and enter the park from the east and then fish your way to Jackson where you will have to fish the Snake towards the west and then your not that far from the Henrys Fork.....which is still on the way to the Missouri...... or fish both Boulder rivers, the one south of Big Timber and the next day farther west out of Boulder, Mt. It will be a great trip.

Just fyi, Beartooth takes a few hours in July to get over to cook. 19-21st is Harley rodeo and packed with bikers and would avoid if your coming around those dates. You would need to pay for a Yellowstone park pass and license. The park is packed that time of year 35-45mph if your lucky.

If rock creek is fishing well I would always recommend it here. The drive and views are hard to beat in Red Lodge. If you like to day hike there are some nice cutts in the area lakes though.